Memory systems may include a plurality of discrete memory devices. Each memory device may include multiple memories. In some systems, the individual memories may be referred to as logical units (LUNs). The LUNs may be organized into memory groups, where each LUN belonging to a memory group receives a common chip enable CE signal. Each memory group may contain one or more LUNs. The common CE signal may be utilized to save layout area and reduce circuit complexity in the memory system by avoiding the need for providing (as used herein, “providing” refers to, for example, generating, issuing, passing, sending, transmitting and the like) separate CE signals to each of the LUNs of a memory group.
A memory controller in the memory system (which may be external to or internal to the memory device) may use command and address signals provided to the memory devices to command the discrete memories to perform memory operations. Memory operations may include read operations for reading stored data from the memories, as well as write operations for writing data to the memories to be stored. The memory controller typically selects a desired LUN in a desired memory group to perform a memory operation, such as reading or writing data to a selected LUN. The memory controller may provide a logic level low CE signal to the desired memory group to activate the LUNs of the memory group. The LUNs may enter an elevated power mode that readies the LUNs to perform a memory operation. Although one of the LUNs will typically be commanded to perform the memory operation, the shared CE signal results in all LUNs in the memory group entering an elevated power mode that draws an increased current compared to a low power mode.
While the unselected LUNs in the memory group may not be performing memory operations, the current drawn by the memory group is nonetheless additive across all of the unselected LUNs, which results in significant power consumption by a memory group. In configurations having memory groups with a high number of LUNs, the power consumption for activating all of the LUNs of the memory group for a memory operation relative to merely one of the LUNs may be significant.